[1] Norwegian Inst Publ Hlth, POB 222 Skoyen, N-0213 Oslo, Norway
[2] Univ Saskatchewan, Coll Med, Sch Rehabil Sci, Suite 3400,3rd Floor,104 Clin Pl, Saskatoon, SK S7N 2Z4, Canada
[3] Univ Santo Tomas, Fac Cultura Fis Deporte & Recreat, Bogota, Colombia
[4] Minist Accra, Ghana Minist Hlth, POB M 44, Accra, Ghana
[5] London Sch Hyg & Trop Med, Keppel St, London WC1E 7HT, England